When the accelerator of a vehicle is depressed to accelerate the vehicle from coasting, i.e. when the vehicle is running after the fuel supply to the engine has stopped, the output torque of the engine changes in steps so that torque shock occurs. In vehicles provided with manual transmission or automatic transmission directly connected to the clutch when the vehicle is coasting, this torque shock may cause the drive shaft or drive system to suffer a twisting oscillation via the clutch. This twisting oscillation causes a forward/backward vibration of the vehicle which makes the driver or passengers uncomfortable.
In order to prevent this forward/backward vibration, Tokkai Sho 60-81446 published by the Japanese Patent Office in 1985 discloses a fuel supply controller having a function for stopping fuel supply to specific cylinders at predetermined intervals when an engine provided with a fuel injector for each cylinder is accelerated from coasting.
For example, by supplying fuel alternately to every other cylinder in this way, the rise of engine output torque is smoothed, and torque shock is reduced.
According to this device, torque shock is reduced, but the reaction of the vehicle to the depression of the accelerator becomes sluggish so that acceleration performance is impaired.
Further, although the cylinders to which fuel supply is stopped are predetermined, the cylinder of which the spark plug is ignited first, is different each time combustion restarts. It is thus a matter of chance whether or not fuel is supplied to the cylinder which ignites first when combustion restarts. However, the stopping of fuel supply for suppressing vibration is only effective for 5-6 times in terms of supply, or 2-3 times in terms of fuel supply cuts, after the restart of combustion. The combustion pattern therefore largely varied depending on whether or not fuel was supplied to the cylinder which ignited first when combustion was restarted, and there was a large scatter in suppression of torque shock.